The present invention relates in general to loudspeaker porting and more particularly concerns a novel loudspeaker system having all the advantages of the commercially available BOSE Model 800 loudspeaker system while reproducing low frequency sound at significant sound levels with reduced driving power with structure that is relatively free from complexity through the use of damping material in the port tube that may be readily changed with a structure that also helps keep the grill in place over the loudspeaker drivers. The present invention incorporates the principles in application Ser. No. 719,949 entitled LOUDSPEAKER SYSTEM of Joseph Veranth filed Sept. 2, 1976, now U.S. Pat. No. 4,146,744.
The present invention represents an advance over the commercially available BOSE 800 professional loudspeaker system that comprises eight high-compliance, full-range drivers connected in phase.
While that system performed well and reproduced sound at high sound levels without audible distortion, the driving power required to produce a given sound level in the bass frequency region was higher than desired. The aforesaid pending application teaches using two reactive air columns ports that function to reduce driver cone excursion at low frequencies and produce high output levels at deep bass frequencies with relatively little distortion and reducing the Q of the port mass-cabinet compliance resonance by placing damping material in each port tube. Although this invention works well, it was discovered that after prolonged use, there was a buzzing sound during heavy bass passages. It was discovered that the cause of this problem was clogging of the damping material. Accordingly, it is an important object of the invention to provide methods and means for overcoming the problem noted above.
It is a further object of the invention to achieve the preceding object with structure that facilitates maintaining a clean passage in the port tube damping means.
It is still a further object of the invention to achieve one or more of the preceding objects with structure that facilitates easy replacement of the damping means.
It is still a further object of the invention to achieve one or more of the preceding objects with structure that also helps detachably secure the grill to the baffle.
It is still another object of the invention to achieve one or more of the preceding objects with structure that may be readily assembled and disassembled without tools.
It is still another object of the invention to achieve one or more of the preceding objects with structure that is free from undesired sympathetic vibrations when reproducing sound at high levels.
It is still another object of the invention to achieve one or more of the preceding objects with attractive structure.
It is still another object of the invention to achieve one or more of the preceding objects with structure that is relatively easy and economical to manufacture.